Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteTo generate shipping-label images automatically, send shipment data to a carrier or shipping platform label endpoint, request an output format such as PNG, PDF or ZPL, then save the returned bytes (or download the returned URL) against the order. Print the file after checking its dimensions and barcode readability. DHL eCommerce returns Base64-encoded PNG or PDF data (or plain-text ZPL) from POST /shipping/v4/label; ShipStation supports PDF, PNG and ZPL in 4×6 or letter layouts; Walmart’s Create label API selects PNG or PDF through the HTTP Accept header.
Choose the API before you write code
Your carrier and sales channel determine the endpoint, authentication and fields. A label API normally needs ship-from and ship-to addresses, package weight and dimensions, shipping service and a unique order or package identifier. Validate addresses and service availability before requesting a label.
| Use case | Documented option | Output and delivery details |
|---|---|---|
| DHL eCommerce domestic or international shipping | DHL eCommerce Label API v4.0.0 | POST /shipping/v4/label; one label per request; unique packageId; PNG and PDF are Base64 in the response, ZPL is plain text; response includes DHL and tracking identifiers. |
| Multiple carriers through one integration | ShipStation Labels API | pdf, png or zpl; 4×6 and letter layouts; retrieve by URL or inline data. ShipStation recommends PDF because all carriers support it, while PNG and ZPL support varies. |
| Walmart Marketplace fulfillment | Walmart Create label API | Returns a tracking number and PDF or image. Request PNG with Accept: application/json,image/png or PDF with Accept: application/json,application/pdf. The documented carrier choices are FedEx and USPS. |
| DHL Freight thermal printing | DHL Freight Print API | PDF and ZPL, including ZPL for 203, 300 and 600 DPI printers. |
Pick PNG, PDF or ZPL
PNG for an image asset
Choose PNG when your warehouse application stores a raster image, displays a preview, or sends an image to another service. Preserve the original binary data; repeatedly converting a PDF to a low-resolution bitmap can damage barcodes.
PDF for broad carrier compatibility
PDF is the safest interchange format when carrier coverage matters. It is suited to desktop and office printers and to ShipStation’s documented 4×6 or letter layouts. Do not assume that a PDF page is 4×6: inspect the page size and configure the printer for the label stock.
Recommended Free Tools
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
ZPL for direct thermal output
ZPL is printer language rather than an ordinary image. Send it to a compatible Zebra-style workflow, and match the printer’s DPI. DHL Freight documents 203, 300 and 600 DPI ZPL output. A PNG viewer or office printer cannot print ZPL correctly without a conversion or printer path.
End-to-end implementation
- Collect shipment data. Store normalized sender and recipient names, street lines, locality, region, postal code, country, weight, dimensions, service and a unique order/package ID.
- Validate before charging. Check required fields, postal-code rules, country and service availability. Reject incomplete addresses with an actionable error rather than creating a label that cannot be delivered.
- Authenticate. Keep API credentials server-side, rotate them, and log a request ID rather than the secret. Use the vendor’s current authentication method and environment.
- Request the representation. Set the vendor’s format or HTTP
Acceptvalue. Request 4×6 for thermal stock or letter for office paper where the API supports a layout. - Decode and persist. Decode Base64 exactly once for DHL PNG/PDF responses. Write bytes in binary mode, associate the file with the order, package ID and tracking number, and record the format and creation time.
- Verify and print. Check that the file is non-empty, the expected page or pixel dimensions are present, and the barcode scans at the intended physical size. Keep a reprint action that uses the stored original.
- Handle lifecycle events. Record voided labels, replacement labels and refunds according to the carrier’s rules. Never silently overwrite an earlier label; retain an audit trail.
DHL eCommerce: generating a label image
DHL eCommerce Label API v4.0.0 creates one domestic or international label per POST /shipping/v4/label request. Every request requires a unique packageId. Ask for PNG when your application needs an image; the response carries the image as Base64, along with DHL and tracking identifiers. Ask for ZPL when the output goes directly to a supported thermal printer.
The exact authentication headers and shipment schema depend on your DHL account configuration, so use the field names and credential method in the current DHL documentation. The processing pattern is:
POST /shipping/v4/label
Authorization: <your DHL credential>
Content-Type: application/json
Accept: application/json
{
"packageId": "a-unique-package-id",
"format": "PNG",
"shipFrom": { "...": "validated sender fields" },
"shipTo": { "...": "validated recipient fields" },
"package": { "...": "weight and dimensions" },
"service": "your-account-service"
}In production, replace the illustrative field groups with the schema enabled for your DHL account; do not guess field names. Parse the response, decode the PNG field from Base64, and save it as label.png. Save the tracking identifier returned by DHL with the same order record.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
ShipStation: one integration, several carriers
ShipStation documents pdf, png and zpl formats, 4x6 and letter layouts, and two download modes: a URL or inline data. Request PDF when portability is more important than an image workflow; choose PNG only when the selected carrier supports it. Treat a URL as temporary unless the documentation for your account guarantees retention: download it immediately, checksum the bytes, and store your own copy.
For a 4×6 operation, test the complete path—API response, file viewer, print driver and physical stock. A layout parameter alone does not correct a printer configured for letter paper.
Walmart Create label API
Walmart’s endpoint returns shipment information, a tracking number and either PDF or image output. Set Accept: application/json,image/png for PNG or Accept: application/json,application/pdf for PDF. The documented carrier support is FedEx and USPS. Keep the tracking number with the file and confirm that your Walmart seller authorization covers the shipment and carrier.
Code patterns for saving returned files
Python: decode an inline Base64 image
import base64
from pathlib import Path
import requests
response = requests.post(
"https://your-carrier.example/shipping/v4/label",
headers={"Authorization": "YOUR_CREDENTIAL", "Accept": "application/json"},
json={"packageId": "unique-package-id", "format": "PNG"},
timeout=60,
)
response.raise_for_status()
data = response.json()
# Use the Base64 property named by your carrier's response schema.
raw_png = base64.b64decode(data["labelBase64"], validate=True)
Path("label.png").write_bytes(raw_png)
print(data.get("trackingNumber"))The property name in this example is intentionally the response field you must map from your carrier’s schema; do not assume every vendor calls it labelBase64.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
cURL: request a Walmart PNG
curl -X POST "https://your-walmart-label-endpoint"
-H "Authorization: Bearer YOUR_TOKEN"
-H "Content-Type: application/json"
-H "Accept: application/json,image/png"
--data-binary @shipment.json
-o label.pngUse the endpoint, token format and JSON fields assigned to your Walmart seller account. For PDF, change only the Accept value to application/json,application/pdf.
Node.js: save a binary response
const fs = require('node:fs/promises');
const res = await fetch('https://your-label-endpoint', {
method: 'POST',
headers: {
Authorization: 'Bearer YOUR_TOKEN',
Accept: 'image/png',
'Content-Type': 'application/json'
},
body: JSON.stringify({ packageId: 'unique-package-id' })
});
if (!res.ok) throw new Error(`Label request failed: ${res.status}`);
const bytes = Buffer.from(await res.arrayBuffer());
await fs.writeFile('label.png', bytes);Reliability, security and operating cost
- Use an idempotency key or your carrier’s documented duplicate-prevention mechanism. If a timeout occurs after submission, query the shipment before creating another label.
- Queue label jobs and retry transient 429 or 5xx responses with exponential backoff. Do not retry validation errors unchanged.
- Encrypt stored labels and restrict access; labels contain names and addresses. Set a retention period that matches operational and legal requirements.
- Track API latency, response status, bytes written, decode failures and print failures. Alert when a successful API response produces an unreadable file.
- Budget for carrier postage and any platform fees separately from image storage and printing. The documentation cited here does not establish independent statistical prices or performance figures.
Troubleshooting
“Invalid package” or validation response
Check the unique packageId, address normalization, country and service, weight units, dimensions and required authentication fields. Log the vendor’s request ID and corrected field-level error.
The saved PNG will not open
Confirm that you decoded Base64 once, opened the file in binary mode and did not save a JSON error body as .png. Check the HTTP status and content type before writing.
The barcode scans on screen but not on paper
Print at the API’s intended physical size, disable “fit to page,” use the correct 4×6 stock, and test the printer’s DPI. Avoid JPEG conversion or aggressive image resizing.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
A URL label has expired
Download URL-based labels immediately and store the bytes. Keep the URL only as metadata, not as your sole copy.
ZPL prints garbage
Send ZPL as plain text to a compatible printer path at the documented DPI. Do not open it as PNG or send it through an office PDF driver.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Or skip the browser setup
ScreenshotNeo is not a carrier label-creation API; it is useful when you already have a hosted label preview or shipping-document page and need a clean image of that page for an internal dashboard, archive or approval queue. One GET request returns PNG, JPEG, WebP or PDF. Cookie banners, newsletter popups and chat widgets are removed before capture; bot checks, blank pages and failed loads are not billed. Its MCP server lets AI agents call take_screenshot, get_page_info and capture_pdf. The free plan includes 1,000 screenshots per month with no card, and paid plans start at $5 for 3,000 shots.
See the ScreenshotNeo API documentation for options such as full-page capture, element selection, custom CSS, waiting for a selector or network idle, and signed links.
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webpReplace the example URL with your authenticated, hosted label-preview URL. Create a free ScreenshotNeo account to get 1,000 screenshots a month without a card.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Pre-production checklist
- Confirm carrier, geography, account permissions and current API version.
- Test domestic and international addresses, every service you offer and duplicate requests.
- Verify 4×6 and letter output on the actual printer or scanner.
- Exercise timeout, rate-limit, invalid-address and expired-URL paths.
- Store tracking number, package ID, original bytes, format, timestamp and reprint status.
Frequently Asked Questions
Can I create a 4×6 shipping label as a PNG?
Yes, when the selected carrier supports PNG. Request the 4×6 layout where the API exposes it, then verify the printed physical dimensions and barcode scan.
Should I request PDF or PNG?
Use PDF for the broadest carrier compatibility; use PNG when your workflow specifically needs an image asset. Carrier support for PNG varies.
Is ZPL an image file?
No. ZPL is printer language for compatible thermal printers, so it must follow a suitable printer path rather than an image viewer.
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchPC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11The Bottom Line
Automated label images come from the carrier or shipping platform, not from a generic image generator: validate shipment data, request the right format and layout, persist the returned bytes with tracking data, and test the physical print before production.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
